We are using Web forms and would like to know if we could reuse/enable Sitecore's built in Anti CSRF token mechanism for the website instead of limiting it's scope to Sitecore itself.. I couldn't find any setting in Sitecore.Anticsrf.config file..
Unfortunately you can't reuse it. It is only for the Content Management server. For Content Editor, Experience Editor and etc... I suggest to you to use another solution for that. For example this one - https://anticsrf.codeplex.com
AntiCSRF makes it easier for ASP.NET developers to guard themselves against Cross Site Request Forgery. You'll no longer have to manually add and check protection tokens to protected yourself against CSRF attacks.